Present a one-factor Ricardian model of two countries, A and B, trading two goods, X and Y, and discuss the gains of trade generated in this model
The modern version of the Ricardian model assumes that there are two countries producing two goods using one factor of production, usually labor. The model is a general equilibrium model in which all markets (i.e., goods and factors) are perfectly competitive. The goods produced are assumed to be homogeneous across countries and firms within an industry. Goods can be costlessly shipped between countries (i.e., there are no transportation costs). Labor is homogeneous within a country but may have different productivities across countries. This implies that the production technology is assumed to differ across countries. Labor is costlessly mobile across industries within a country but is immobile across countries. Full employment of labor is also assumed. Consumers (the laborers) are assumed to maximize utility subject to an income constraint. For example, we should think of two countries that both make cards and pencils and use the same amount of time to make one unit of items (please see table). Country one can make 4 pencils if they specialize just in pencils at the expense of one card, but this country can also make ¼ of a card at the expense of one pencil. The same logic goes for country two: if country two makes only pencils, it will make 2 pencils at the expense of 1 card. If country two specializes only in cards, it will make ½ of a card at the expense of a pencil. For this example, country one has a comparative advantage in pencils over country two (4 pencils to 2 pencils), whereas, country two has a comparative advantage in cards over country one (½ of a card to ¼ of a card). In Ricardo's idea of comparative advantage, these two countries should specialize in what they do best.